1. Field of the Invention
The present invention is directed to a coil system for magnetic resonance systems which surrounds a substantially cylindrical examination volume, of the type having coil plies formed by the X-gradient coils arranged symmetrically relative to the YZ plane and spaced from one another, Y-coils arranged symmetrically relative to the XZ plane and spaced from one another and Z coils arranged symmetrically relative to the XY plane and spaced from one another, and that has indirect cooling by embedded cooling conduits through which a coolant flows.
2. Description of the Prior Art
In order to guarantee a maximally permitted temperature of a magnetic resonance coil system, it is necessary to eliminate the high dissipated electrical power that occur.
Direct cooling is employed for this purpose, but this is relatively complicated in structure and is often also very complicated and expensive to operate, wherein the electrical conductors of the coil windings are provided with internal cooling channels. Less efficient air cooling is also used, as disclosed, for example, in German OS 195 47 279. Given this indirect cooling, either the cooling conduits (see, for example, German OS 34 45 448 A1) are integrated into the interspaces of the conductor structures of a coil ply, or copper cooling coils are placed in serpentine fashion along the longitudinal direction between individual coil plies, or plastic hoses are helically wound between the coil plies (German OS 196 41 319). The effectiveness of this cooling is limited in both instances, since the heat to be eliminated from the source to the sink, i.e. from the warmest location to the layer of the cooling conduits, must penetrate all layers lying therebetween. In the case of the helically wound plastic hoses, the efficiency is even poorer than that of the flat copper tubes because of the thermal resistance of the plastic hoses.